diff --git a/lib/remote_storage/swift.rb b/lib/remote_storage/swift.rb
index 679d8b7..0a41055 100644
--- a/lib/remote_storage/swift.rb
+++ b/lib/remote_storage/swift.rb
@@ -159,6 +159,7 @@ module RemoteStorage
       if update_metadata_object(user, directory, key, metadata)
         if metadata_changed?(existing_metadata, metadata)
           update_dir_objects(user, directory, timestamp, checksum_for(data))
+          log_size_difference(user, existing_metadata["s"], metadata[:s])
         end
 
         server.headers["ETag"] = %Q("#{res.headers[:etag]}")
@@ -168,6 +169,11 @@ module RemoteStorage
       end
     end
 
+    def log_size_difference(user, old_size, new_size)
+      delta = new_size.to_i - old_size.to_i
+      redis.incrby "rs:s:#{user}", delta
+    end
+
     def checksum_for(data)
       Digest::MD5.hexdigest(data)
     end
@@ -182,6 +188,7 @@ module RemoteStorage
       end
 
       do_delete_request(url)
+      log_size_difference(user, existing_metadata["s"], 0)
       delete_metadata_objects(user, directory, key)
       delete_dir_objects(user, directory)
 
diff --git a/spec/swift/app_spec.rb b/spec/swift/app_spec.rb
index a30c52e..eadbc68 100644
--- a/spec/swift/app_spec.rb
+++ b/spec/swift/app_spec.rb
@@ -74,6 +74,36 @@ describe "App" do
         root_items.must_equal ["food/"]
       end
 
+      context "logging usage size" do
+        before do
+          @put_stub = OpenStruct.new(headers: {
+            etag: "bla",
+            last_modified: "Fri, 04 Mar 2016 12:20:18 GMT"
+          })
+
+        end
+
+        it "logs the complete size when creating new objects" do
+          RestClient.stub :put, @put_stub do
+            put "/phil/food/aguacate", "1234567890"
+          end
+
+          size_log = redis.get "rs:s:phil"
+          size_log.must_equal "10"
+        end
+
+        it "logs the size difference when updating existing objects" do
+          RestClient.stub :put, @put_stub do
+            put "/phil/food/camaron",  "1234567890"
+            put "/phil/food/aguacate", "1234567890"
+            put "/phil/food/aguacate", "123"
+          end
+
+          size_log = redis.get "rs:s:phil"
+          size_log.must_equal "13"
+        end
+      end
+
       describe "objects in root dir" do
         before do
           put_stub = OpenStruct.new(headers: {
@@ -289,6 +319,17 @@ describe "App" do
         end
       end
 
+      it "decreases the size log by size of deleted object" do
+        RestClient.stub :delete, "" do
+          RemoteStorage::Swift.stub_any_instance :etag_for, "rootetag" do
+            delete "/phil/food/aguacate"
+          end
+        end
+
+        size_log = redis.get "rs:s:phil"
+        size_log.must_equal "8"
+      end
+
       it "deletes the metadata object in redis" do
         RestClient.stub :delete, "" do
           RemoteStorage::Swift.stub_any_instance :etag_for, "rootetag" do